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<p>In a <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">class</span></span></span> or <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">struct</span></span></span> body define the visibility of following declarators
In a inheritance list, define the maximum visibility of inherited members
</p>
<table id="toc" class="toc"><tr><td>
<div id="toctitle"><h2>Contents</h2></div>
<ul>
<li class="toclevel-1 tocsection-1"><a href="access.html%23Syntax"><span class="tocnumber">1</span> <span class="toctext">Syntax</span></a></li>
<li class="toclevel-1 tocsection-2">
<a href="access.html%23Explanation"><span class="tocnumber">2</span> <span class="toctext">Explanation</span></a>
<ul>
<li class="toclevel-2 tocsection-3"><a href="access.html%23Member_accessibility_by_specifier"><span class="tocnumber">2.1</span> <span class="toctext">Member accessibility by specifier</span></a></li>
</ul>
</li>
<li class="toclevel-1 tocsection-4"><a href="access.html%23Public_member_access"><span class="tocnumber">3</span> <span class="toctext">Public member access</span></a></li>
<li class="toclevel-1 tocsection-5"><a href="access.html%23Protected_member_access"><span class="tocnumber">4</span> <span class="toctext">Protected member access</span></a></li>
<li class="toclevel-1 tocsection-6"><a href="access.html%23Private_member_access"><span class="tocnumber">5</span> <span class="toctext">Private member access</span></a></li>
<li class="toclevel-1 tocsection-7"><a href="access.html%23Public_inheritance"><span class="tocnumber">6</span> <span class="toctext">Public inheritance</span></a></li>
<li class="toclevel-1 tocsection-8"><a href="access.html%23Protected_inheritance"><span class="tocnumber">7</span> <span class="toctext">Protected inheritance</span></a></li>
<li class="toclevel-1 tocsection-9"><a href="access.html%23Private_inheritance"><span class="tocnumber">8</span> <span class="toctext">Private inheritance</span></a></li>
</ul>
</td></tr></table>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: Syntax">edit</a>]</span> <span class="mw-headline" id="Syntax">Syntax</span>
</h3>
<table class="t-sdsc-begin">

<tr>
<td colspan="10" class="t-sdsc-sep">
</td>
</tr>
<tr class="t-sdsc">
<td> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">public</span><span class="sy4">:</span></span></span> <span class="t-spar">declarators</span>
</td>
<td> (1)
</td>
<td class="t-sdsc-nopad">
</td>
</tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td>
</tr>
<tr class="t-sdsc">
<td> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">protected</span><span class="sy4">:</span></span></span> <span class="t-spar">declarators</span>
</td>
<td> (2)
</td>
<td class="t-sdsc-nopad">
</td>
</tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td>
</tr>
<tr class="t-sdsc">
<td> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">private</span><span class="sy4">:</span></span></span> <span class="t-spar">declarators</span>
</td>
<td> (3)
</td>
<td class="t-sdsc-nopad">
</td>
</tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td>
</tr>
<tr class="t-sdsc">
<td> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">class</span></span></span> <span class="t-spar">identifier</span> <code>:</code> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">public</span></span></span> <span class="t-spar">class_name</span>
</td>
<td> (4)
</td>
<td class="t-sdsc-nopad">
</td>
</tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td>
</tr>
<tr class="t-sdsc">
<td> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">class</span></span></span> <span class="t-spar">identifier</span> <code>:</code> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">protected</span></span></span> <span class="t-spar">class_name</span>
</td>
<td> (5)
</td>
<td class="t-sdsc-nopad">
</td>
</tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td>
</tr>
<tr class="t-sdsc">
<td> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">class</span></span></span> <span class="t-spar">identifier</span> <code>:</code> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">private</span></span></span> <span class="t-spar">class_name</span>
</td>
<td> (6)
</td>
<td class="t-sdsc-nopad">
</td>
</tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td>
</tr>
</table>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: Explanation">edit</a>]</span> <span class="mw-headline" id="Explanation">Explanation</span>
</h3>
<ol>
<li> The symbols declared after the specifier have public accessibility
</li>
<li> The symbols declared after the specifier have protected accessibility
</li>
<li> The symbols declared after the specifier have private accessibility
</li>
<li> The inherited members have the same accessibility as the base class ( either protected or public as private won't be visible in the derived class )
</li>
<li> The inherited members have protected accessibility in the derived class
</li>
<li> The inherited members have private accessibility in the derived class
</li>
</ol>
<h4>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: Member accessibility by specifier">edit</a>]</span> <span class="mw-headline" id="Member_accessibility_by_specifier">Member accessibility by specifier</span>
</h4>
<dl>
<dt>public
</dt>
<dd>public members are accessible everywhere, within and outside the class scope
</dd>
<dt>protected
</dt>
<dd>protected members are accessible within the class and its methods and in its descendants
</dd>
<dt>private
</dt>
<dd>private members can be only accessed within the class and its methods
</dd>
</dl>
<p>To grant access to external functions or classes to protected or private members, a <a href="friend.html" title="cpp/language/friend">friendship declaration</a> must be present in the class body
</p>
<p>Inherited private members are still present in the class data but cannot be accessed directly
</p>
<p>A <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">class</span></span></span> has default private accessibility for inheritance and members, a <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">struct</span></span></span> has instead a default public accessibility
</p>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: Public member access">edit</a>]</span> <span class="mw-headline" id="Public_member_access">Public member access</span>
</h3>
<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style=""><tr>
<td class="mbox-empty-cell"></td>
<td class="mbox-text" style="">This section is incomplete </td>
</tr></table>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: Protected member access">edit</a>]</span> <span class="mw-headline" id="Protected_member_access">Protected member access</span>
</h3>
<p>Protected members form the interface for the derived classes (which is distinct from the public interface of the class).
</p>
<p>A protected member of a class <code>Base</code> can only be accessed
</p>
<div class="t-li1">
<span class="t-li">1)</span> by the member functions and friend functions of <code>Base</code> </div>
<div class="t-li1">
<span class="t-li">2)</span> by the member functions and friend functions of any class derived from <code>Base</code>, but only when operating on an object of a type that is derived from <code>Base</code> (including <code>this</code>)</div>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="cpp source-cpp"><pre class="de1"><span class="kw1">struct</span> Base <span class="br0">{</span>
 <span class="kw1">protected</span><span class="sy4">:</span>
    <span class="kw4">int</span> i<span class="sy4">;</span>
 <span class="kw1">private</span><span class="sy4">:</span>
    <span class="kw4">void</span> g<span class="br0">(</span>Base<span class="sy3">&amp;</span> b, <span class="kw1">struct</span> Derived<span class="sy3">&amp;</span> d<span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span><span class="sy4">;</span>
 
<span class="kw1">struct</span> Derived <span class="sy4">:</span> Base <span class="br0">{</span>
    <span class="kw4">void</span> f<span class="br0">(</span>Base<span class="sy3">&amp;</span> b, Derived<span class="sy3">&amp;</span> d<span class="br0">)</span> <span class="co1">// member function of a derived class</span>
    <span class="br0">{</span>
        <span class="sy2">++</span>d.<span class="me1">i</span><span class="sy4">;</span> <span class="co1">// okay: the type of d is Derived</span>
        <span class="sy2">++</span>i<span class="sy4">;</span> <span class="co1">// okay: the type of the implied '*this' is Derived</span>
<span class="co1">//      ++b.i; // error: can't access a protected member through Base</span>
    <span class="br0">}</span>
<span class="br0">}</span><span class="sy4">;</span>
 
<span class="kw4">void</span> Base<span class="sy4">::</span><span class="me2">g</span><span class="br0">(</span>Base<span class="sy3">&amp;</span> b, Derived<span class="sy3">&amp;</span> d<span class="br0">)</span> <span class="co1">// member function of Base</span>
<span class="br0">{</span>
    <span class="sy2">++</span>i<span class="sy4">;</span> <span class="co1">// okay</span>
    <span class="sy2">++</span>b.<span class="me1">i</span><span class="sy4">;</span> <span class="co1">// okay</span>
    <span class="sy2">++</span>d.<span class="me1">i</span><span class="sy4">;</span> <span class="co1">// okay</span>
<span class="br0">}</span>
 
<span class="kw4">void</span> x<span class="br0">(</span>Base<span class="sy3">&amp;</span> b, Derived<span class="sy3">&amp;</span> d<span class="br0">)</span> <span class="co1">// non-member non-friend</span>
<span class="br0">{</span>
<span class="co1">//    ++b.i; // error: no access from non-member</span>
<span class="co1">//    ++d.i; // error: no access from non-member</span>
<span class="br0">}</span></pre></div></div>
<p>When a pointer to a protected member is formed, it must use a derived class in its declaration:
</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="cpp source-cpp"><pre class="de1"><span class="kw1">struct</span> Base <span class="br0">{</span>
 <span class="kw1">protected</span><span class="sy4">:</span>
    <span class="kw4">int</span> i<span class="sy4">;</span>
<span class="br0">}</span><span class="sy4">;</span>
 
<span class="kw1">struct</span> Derived <span class="sy4">:</span> Base <span class="br0">{</span>
    <span class="kw4">void</span> f<span class="br0">(</span><span class="br0">)</span>
    <span class="br0">{</span>
<span class="co1">//      int Base::* ptr = &amp;Base::i;    // error: must name using Derived</span>
        <span class="kw4">int</span> Base<span class="sy4">::</span><span class="sy2">*</span> ptr <span class="sy1">=</span> <span class="sy3">&amp;</span>Derived<span class="sy4">::</span><span class="me2">i</span><span class="sy4">;</span> <span class="co1">// okay</span>
    <span class="br0">}</span>
<span class="br0">}</span><span class="sy4">;</span></pre></div></div>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: Private member access">edit</a>]</span> <span class="mw-headline" id="Private_member_access">Private member access</span>
</h3>
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<td class="mbox-empty-cell"></td>
<td class="mbox-text" style="">This section is incomplete </td>
</tr></table>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: Public inheritance">edit</a>]</span> <span class="mw-headline" id="Public_inheritance">Public inheritance</span>
</h3>
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<td class="mbox-empty-cell"></td>
<td class="mbox-text" style="">This section is incomplete </td>
</tr></table>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: Protected inheritance">edit</a>]</span> <span class="mw-headline" id="Protected_inheritance">Protected inheritance</span>
</h3>
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<td class="mbox-empty-cell"></td>
<td class="mbox-text" style="">This section is incomplete </td>
</tr></table>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: Private inheritance">edit</a>]</span> <span class="mw-headline" id="Private_inheritance">Private inheritance</span>
</h3>
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<td class="mbox-empty-cell"></td>
<td class="mbox-text" style="">This section is incomplete </td>
</tr></table>
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<td class="mbox-empty-cell"></td>
<td class="mbox-text" style="">This section is incomplete<br>Reason: example </td>
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